A kampo preparation is a pharmaceutical prepared by blending crude drugs, in which all the active ingredients are not always specifically identified. Furthermore, a single active ingredient alone does not always exhibit its effect, and some active ingredients may compositely act with each other. For assuring its quality, it is said that an assay method capable of totally evaluating the whole kampo preparation is necessary. Indeed, the U.S. Food and Drug Administration Guidance for Industry on Botanical Drug Products calls for a quality control using a bioassay and the like for products such as kampo preparations.
Assay methods include a method that measures and comprehensively evaluates all the components thought to have efficacy, and a bioassay method of evaluating the physiological activity by the use of a biological material. The former method is problematic in terms of measurement costs and establishing a measurement method. Bioassay methods include an in-vivo test and an in-vitro test, and the in-vivo test system has many limitations regarding the test facilities, test animals, the processing capability, and the like, and there are difficulties in applying the in-vivo test to the quality evaluation of kampo preparations.
On the other hand, the in-vitro test system does not require any special facilities and gives stable test results in a short period of time. For this reason, an in-vitro bioassay method is desirable. However, for a kampo preparation that comprises a combination of crude drugs each having plural active ingredients, a suitable bioassay system has not yet been reported, and such a bioassay system is desired.
To date, a method that directly measures the contraction of enteric smooth muscle following Daikenchuto administration (the Magnus method) has been established as a bioassay method for the quality control of the pharmacological effect of the kampo preparation Daikenchuto (Non-Patent Document 1).
However, because the Magnus method uses the intestinal tract isolated from a rat, it has poor utility as a bioassay method conducted as a routine test for quality evaluation, and is insufficient in terms of qualities such as sensitivity and reproducibility.